As broadly known, over the recent years, a disk array device including a plurality of RAID groups has come to be used for managing (keeping) data for a variety of services, and business data.
Such a type of disk array device also needs to rewrite firmware of drives (normally, hard disk drives) configuring each RAID group as the case may be. It is not, however, preferable to stop a RAID group (to set a RAID group in an inaccessible status) of the disk array device used for managing the data for the services and the business data in order to rewrite the firmware.
Then, the RAID group having redundancy (the RAID group having RAID level other than RAID 0) may function as a storage device even when stopping one single drive. A device is therefore developed, which rewrites the firmware of the drives configuring the RAID group having the redundancy without stopping the RAID group.
The existing device has, however, a possibility to cause a phenomenon such as “data lost”, depending on input timing of a firmware rewrite command.